The problems of localization and mapping have been studied for decades, with a variety of intricate hand-designed models and algorithms being developed, for example, odometry estimation (including visual odometry [1]}, [2]}, [3]}, visual-inertial odometry [4]}, [5]}, [6]}, [7]} and LIDAR odometry [8]}), image-based localization[9]}, [10]}, place recognition[11]}, SLAM[12]}, [2]}, [14]}, and structure from motion (SfM)[15]}, [16]}.
Under ideal conditions, these sensors and models are capable of accurately estimating system states without time bound and across different environments.
However, in reality, imperfect sensor measurements, inaccurate system modelling, complex environmental dynamics and unrealistic constraints impact both the accuracy and reliability of hand-crated systems.
